SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758352caaae26ad5cdcfc49ed2e37821d8617144ca96545629b7136a9812ae04' 
  AND token = 'xOSvzLfWQ5xl4qCsdw+GgHljnhYh1P/Gwp+IgKxEn+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}